I was in a store today, buying one thing. I got in the line behind a couple of other people. One person moved up, and I was the next in line. Stood there for a few minutes as the guy ahead of me checked out several items. But then I noticed that another person had come up and was standing sort of in front of the check-out counter and behind the person being served, but off to the other side, like she was next. (Think of it like one check-out counter with now two lines shooting off from it, like a 'V'.)

So the clerk finished and asked who was next and I just said 'I think I was' and moved forward. I never really looked at the other person, nor did she say anything. Frankly, I WAS there first and didn't want to wait any longer. Within probably 30 seconds, my transaction was completed and I was out of there. But I started thinking.....

Is it common politeness to engage with the other person for something like this? I felt if I looked at her, then if she told me to go first, then I feel like I'd have to thank her, and that just seemed stupid, when I really WAS there first; it would be like thanking her for not cutting (if we all went around thanking people for not doing things they shouldn't do anyway, the world would be a very polite place, but heck, we'd never get anything done!). For interactions like this, it seems that the 'polite' thing is to look at the other person to say, 'who was first?' or 'were you here before me?'; basically play dumb even though you know darn well that you were first. And there are some people who will take advantage of that. So, knowing that, I just opted to assert myself and all was well.

But if you know you're in the right and you really WERE next in line, does etiquette dictate that you engage with the other person who either knowingly or unknowingly tried to cut or create her own line? Or is asserting your right to be served next perfectly fine?

(The other guy in front of me had a cart with stuff, and I was behind him. I have no idea why the other lady didn't think that looked like an already-formed checkout line, but whatever.)

Maybe she thought you were together, since you were standing there with one item which she may or may not have seen.

Then again, I've had people do weird things like this in coffee lineups. I think you did fine, though I probably would have at least glanced at the person to acknowledge their presence while stating I was next. I don't think it's necessary though.

I find it very strange that she stood to the side of the check-out line (if I'm understanding the situation correctly). It's possible that she was from a foreign country, or extremely sheltered, and didn't know how a check-out line works (but highly unlikely). Or it's possible she was just trying to push her way in (more likely).

You were definitely next, but I don't suppose the other person was waiting for something else, not standing in line to be checked out?Only because the other day I was at the chemist buying a couple of lip glosses, and the cashier pointed out they were buy two get a third free, and told me to go grab a third and just to show it to her on the way out (without her needing to scan it) - I didn't line up again, but walked past the front of the line and waved it at her as I walked past. A few times I've bought something and noticed at the checkout that it needed to be replaced (accidentally grabbed a leaking carton, for example), and generally the cashier will scan the faulty item and tell me to grab a replacement on my way out and just show it to her - I wouldn't line up a second time for that nor would I be expected to (at least not here).

Of course it's likely she was trying to line-jump or somehow didn't realise where the line was - and definitely the OP was in the right. I'm just saying hypothetically it's possible she had a reason to be standing there.

Was there just the one till open? I have seen people become confused where there are two tills next to each other, and they aren't sure if there's one queue for both tills, or if each till has its own queue. But it sounds like there was just one, in which case, you were fine.